1. Field
The present disclosure relates to a cap, which covers a lift hole of a lifting lug of a hollow slab.
2. Description of Related Art
For lifting and moving of hollow-core slabs and massive slabs it is often necessary to provide the ready cast slabs with lifting lugs. Lifting lugs are positioned to the cast hollow-core slab at the hollow cores as shown in the EP 1878854 or on the bracket between the hollow cores as shown in the FR 2905397, whereby the upper surface of the slab is removed at a predetermined place and predetermined length at the hollow core or the bracket of the hollow-core slab, the opened ends of the hollow core are plugged, e.g., by means of plugs made of plastic or by means of added concrete mass, and the lifting lug is positioned to the provided space.
At the construction site, the ready cast slabs with lifting lugs are mounted in their places, where the space of the hollow-core slabs defined by the plugs is filled with concrete mass up to the level of the upper surface of the hollow-core slab. The lifting lug comprises a cup-like portion having its upper edges limited to the level of the upper surface of the hollow-core slab, and the lug portion of the lifting lug sets itself substantially in the middle of the cup, so that the uppermost part thereof is located substantially at the level of the upper surface of the cast hollow-core slab.
There is a problem when the space of the lifting lugs is filled with concrete mass. The concrete mass spreads into cavities of the hollow-core slabs by partially filling the cavities that will make the structure of the hollow-core slabs heavier. And when the concrete mass spreads into the cavities of the hollow-core slabs, more filling concrete mass is needed.
There is a known solution for the cap where the cap is mounted at the cast slab during its manufacture through the lifting lug, in which the lifting lug is positioned on the bracket between the cavities of the hollow-core slab. The cap has upwards directed bristles which block the flow of the filling concrete mass into the cavities in a lateral direction, and the bracket of the hollow-core slab blocks the flow of the filling concrete mass in a downward direction.
There is another problem when then hollow-core slabs are stored outdoors. The lift hole of the lifting lug is exposed to environmental influences because the hole is uncovered. When it's raining or snowing, water and snow gets into the cavities of the hollow-core slabs causing problems in the long run, such as corrosion and erosion, for example.